They both come from a foreign country to ours.

Same thing

foriegn plants are imported and not indigeno7us to south africa ie blue gums (eucalptus) came from australia.........invaders are the same thing but have certain cgaracteristics that causes them to flourish in their new enviroment so that they take over and end up destroying the indigenous plants..........

Its a bit like the Europeans who were invited to South Africa(by the first settlers) ...they were foreign but got used to the country....and the invaders are those who creep over the borders without an invite...and they multiply in numbers.

Foreign plants come from another country, but unless they take over indigenous vegetation or cause other problems, they are not really invaders, e.g. roses. Invader plants are those that start casuing havoc in agricultural areas, take over indigenous forests, rivers or dams, etc, e.g. jacarandas, eucalyptus, water hyacinth, black wattle, etc

The one is Australian and the other is Russian

A foreign, or alien, plant is one that is not indigenous to the locality. An invasive plant is, as duits wrote, one that takes over (invades) a particular region or habitat. Thus if we combine the two we get an alien invasive and these are plants that are not only not indigenous but are invasive to boot. Not all weeds are invasive though they might be pests but a good example of invasive ones might be white stinkwood (indigenous) which spreads its very fertile seeds far and wide, or black wattle, hakea and Port Jackson willow (aliens). There is a good list of alien invasives at http://www.sana.co.za/Alien-Invasive-Plants/

Agree with CD...

There is no difference they both mean the same.....

Foreign plants jogged to get here whereas invader plants stampeded across your border like the crusaders to get to your land. You in the art and physiology of locomotion foreign and invader plants are very similar. The primary difference is whether they are running types or walking types but their floral intention is to come to your land. What I would do under such circumstances is to stand at the gate and tell both foreign and invader plants to get off my planet.

Source: Planeterian